If $x \oslash y = x+3y$ and $x \boxdot y = x(y-4)$, find $(4 \boxdot 0) \oslash 3$.
First, find $4 \boxdot 0$ $ 4 \boxdot 0 = 4(0-4)$ $ \hphantom{4 \boxdot 0} = -16$ Now, find $-16 \oslash 3$ $ -16 \oslash 3 = -16+(3)(3)$ $ \hphantom{-16 \oslash 3} = -7$.